Francisco Abad

Multi-viewer gesture-based interaction for omni-directional video

Omni-directional video (ODV) is a novel medium that offers viewers a 360º panoramic recording. This type of content will become more common within our living rooms in the near future, seeing that immersive displaying technologies such as 3D television are on the rise. However, little attention has been given to how to interact with ODV content. We present a gesture elicitation study in which we asked users to perform mid-air gestures that they consider to be appropriate for ODV interaction, both for individual as well as collocated settings. We are interested in the gesture variations and adaptations that come forth from individual and collocated usage. To this end, we gathered quantitative and qualitative data by means of observations, motion capture, questionnaires and interviews. This data resulted in a user-defined gesture set for ODV, alongside an in-depth analysis of the variation in gestures we observed during the study.

Learning Words Using Augmented Reality

This paper presents an Augmented Reality (AR) game for learning words. Thirty-two children played the AR game and the equivalent real game. We have compared the results of the two games. The results indicate that children did not found significant differences between the two games except for one question, but 81% of the children liked most the AR game.

Tangible Cubes Used as the User Interface in an Augmented Reality Game for Edutainment

In this paper, we present an Augmented Reality (AR) game for finding and learning about endangered animals in a fun way. It uses tangible cubes as the user interface. This game was included in the activity program of the Summer School of the Universidad Politecnica de Valencia. Forty-six children played the AR game and the equivalent real game. We have compared the results of the two games. The results indicate that children enjoyed playing the AR game more than playing the real game and that they perceived the AR game to be more fun than the real game. They also preferred the AR game to the real one. The children perceived the real game as being easier to play than the AR game. The children also seemed to learn about the subject of endangered animals.

Camera Calibration Using Two Concentric Circles

We present a simple calibration method for computing the extrinsic parameters (pose) and intrinsic parameters (focal length and principal point) of a camera by imaging a pattern of known geometry. Usually, the patterns used in calibration algorithms are complex to build (three orthogonal planes) or need a lot of features (checkerboard-like pattern). We propose using just two concentric circles that, when projected onto the image, become two ellipses. With a simple mark close to the outer circle, our algorithm can recover the full pose of the camera.

Integrating synthetic objects into real scenes

Abstract This paper presents a methodology for integrating synthetic objects into real scenes. We take a set of photographs of the real scene and build a simple image-based model. We use high dynamic range images to build an accurate representation of the lighting in the scene. Then we insert a synthetic object into the model and compute its illumination and shading using the lighting information. Illumination changes produced by the synthetic object are also applied to real-scene objects located nearby. We show how easy it is to achieve photo-realistic results without specialized hardware. Our approach takes advantage of techniques like automatic camera calibration, high dynamic range image capture and image-based lighting.

Tools for Procedural Generation of Plants in Virtual Scenes

Creating interactive graphics applications that present to the user realistic natural scenes is very difficult. Natural phenomena are very complex and detailed to model, and using traditional modeling techniques takes huge amounts of time and requires skilled artists to obtain good results. Procedural techniques allow to generate complex objects by defining a set of rules and selecting certain parameters. This allows to speed up the process of content creation and also allows to create objects on-the-fly, when needed. On-demand generation of scenes enables the authors to create potentially infinite worlds. This survey identifies the main features of the most used systems that implement procedural techniques to model plants and natural phenomena and discuss usability issues.

Procedural Graphics Model and Behavior Generation

Todays virtual worlds challenge the capacity of human creation. Trying to reproduce natural scenes, with large and complex models, involves reproducing their inherent complexity and detail. Procedural generation helps by allowing artists to create and generalize objects for highly detailed scenes. But existing procedural algorithms can not always be applied to existing applications without major changes. We introduce a new system that helps include procedural generation into existing modeling and rendering applications. Due to its design, extensibility and comprehensive interface, our system can handle users objects to create and improve applications with procedural generation of content. We demonstrate this and show how our system can generate both models and behaviours for a typical graphics application.

An enhanced vegetation cover method for automatic generation of land surface emissivity maps

The remote sensing measurement of the land surface temperature from satellites provides an overview of this magnitude on a continuous and regular basis. The study of its evolution in time and space is a critical factor in many scientific fields such as weather forecasting, detection of forest fires, climate change, and so on. The main problem of making this measurement from satellite data is the need to correct the effects of the atmosphere and the surface emissivity. The aim was to define an enhanced vegetation cover method to calculate and generate, automatically, maps of land surface emissivity from images of the AATSR (Advanced Along Track Scanning Radiometer) onboard the Envisat satellite. For the production of these emissivity maps, the geometric model purposed is based on [6]. Its validation was made by comparing the obtained results and the values measured in previous field campaigns [2] carried out in the area of rice fields of Valencia, Spain.

Modeling and Rendering of DPP-Based Light Fields

Autostereoscopic displays are a subject of recent research efforts in computer graphics. Such displays have to be fed graphics information in order to produce spatial images. This information is typically 4D radiance data called a light field. Traditionally light-field models were based on the two-plane parameterization. In this paper, however, we present a light-field representation that is based on the direction-and-point parameterization. This parameterization has certain uniformity properties that produce better rendering results. We describe the files and data structures needed to store the representation, and we introduce a rendering algorithm that takes advantage of the uniformity properties of the direction-and-point parameterization. Our algorithm runs in real time and renders light-field models that look like their geometric counterparts

On the Integration of Synthetic Objects with Real-World Scenes

This paper presents a method for integrating synthetic objects in real-world photographs. We take a set of photographs of a real scene and build a simple image-based model. We use high dynamic range images to build an accurate representation of the lighting in the scene. Then we insert a synthetic object into the model and compute its illumination and shading using the lighting information. Illumination changes produced by the synthetic object are also applied to the background plane in the real-world photograph. We show how easy it is to achieve photorealistic results without specialized hardware. Our approach takes advantage of techniques like automatic camera calibration, high-dynamic range image capture and image-based lighting. We show preliminary results obtained with our application. We also present two improvements that we are currently studying. They are aimed at improving the quality of the resulting images and decreasing the computational resources needed by the process.